Stamping tool, casting mold and methods for structuring a surface of a work piece

ABSTRACT

A simple, cost-effective stamping or molding in the nanometer range is enabled using a stamping surface or molding face with a surface layer having hollow chambers that have been formed by anodic oxidation.

Notice: This application is a reissue divisional of application Ser. No.12/213,990, which is an application for reissue of U.S. Pat. No.7,066,234. More than one reissue application has been filed for thereissue of U.S. Pat. No. 7,066,234. In particular, three applicationsfor reissue of U.S. Pat. No. 7,066,234 have been filed. The reissueapplications are application Ser. No. 12/213,990 filed on Jun. 26, 2008and a divisional reissue of the broadening reissue of U.S. Pat. No.7,066,234 (Ser. No. 12/213,990) filed on Apr. 28, 2010 (the presentapplication), and a continuation reissue of the broadening reissue ofU.S. Pat. No. 7,066,234 (Ser. No. 12/213,990) filed on Apr. 28, 2010(the serial number of which is unknown).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International PatentApplication No. PCT/EP02/07240 filed Jul. 1, 2002, which designated theUnited States and of International Patent Application No. PCT/EP01/04650Apr. 25, 2001 which designated the United States.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stamping tool having a structuredstamping surface, a casting mold, a method for producing a stamping toolor a casting mold having a structured stamping surface, and methods forstructuring a surface of a work piece.

2. Description of Related Art

Stamping constitutes a non-cutting manufacturing method for producing arelief-like or structured surface on a work piece. A stamping tool witha profiled or structured stamping surface is used for this. The stampingsurface is pressed with such a stamping force onto the surface to bestructured of the work piece or rolled on it, so that the work piecebecomes plastic and flows into depressions in the stamping tool or thestamping surface. Due to the considerable stamping forces employed, thestamping tool and the stamping surface are usually made of metal.

Further, molding is known. A casting mold with a structured molding facecan be used for producing a cast work piece with a structured surface bycasting.

In the present invention, nanometer range is understood to meanprofiling or structuring with structural widths of less than 1000 nm,especially of less than 500 nm. The structural width designates thedimension by which individual structural elements, such as bumps, arerepeated, that is, for example, the average distance of adjacent bumpsfrom one another or of depressions from one another.

It is very expensive to manufacture a stamping tool with a very finelystructured or profiled stamping surface. To create a so-called “moth eyestructure”—evenly arranged, egg carton-like bumps—or fine grooves in thenanometer range, it is known from practice to use a lighting patternwith periodic intensity modulation for illuminating photosensitivematerial via two interfering laser beams. After the illuminated materialdevelops, a periodic surface structure results, which is molded intoother materials using various replication methods and finally intonickel, for example, by electroforming. This type of manufacturing isvery expensive and is suited only for structuring even surfaces.

In the nanometer range, lithographic methods for structuring a stampingsurface of a stamping tool can still only be used in a limited way. Itshould be noted here that the wavelength of the visible light alone isalready 400 to 750 nm. In each case, lithographic methods are verycostly.

German Patent DE 197 27 132 C2 discloses the manufacturing of a stampingtool by means of electrolytic machining. During electrolytic machining,a metallic stamping surface of the stamping tool is treatedelectrolytically, wherein, being an anode in a fast-flowing electrolyte,the metal of the stamping surface is located at a minimal distanceopposite a cathode and is dissolved in surface terms. The metal or thestamping surface contains the structure determined by the form of thecathode, and the cathode thus forms a recipient vessel that is shapedelectrochemically. German Patent DE 197 27 132 C2 also provides the useof a cylindrical rotation electrode, whose covering surface presents anegative form of the desired stamping structure. Here, too, there isconsiderable expense involved and structuring in the nanometre range isat least only partly possible.

The use of anodally oxidized surface layers made of aluminum ormagnesium in casting molds to increase resistance is known from SwissPatent CH 251 451. However, the forming of hollow chambers by oxidationfor structuring a molded article in the nanometer range is notdisclosed.

Forming hollow chambers by anodic oxidation of aluminum is described inpublished European Patent Application EP 0 931 859 A1, for example.

However, the related art does not provide a cost-effective solution toproduction of a work piece, like a stamped piece, or casting with asurface structured in the nanometer range.

Consequently, there is a need for a stamping tool, a casting mold, amethod for manufacturing a stamping tool or a casting mold, a method forstructuring a surface of a work piece and a method for using a surfacelayer provided with open hollow chambers, wherein structuring in thenanometer range is enabled in a simple and cost-effective manner.

SUMMARY OF INVENTION

A primary object of the present invention is to provide a stamping tool,a casting mold, a method for manufacturing a stamping tool or a castingmold, a method for structuring a surface of a work piece and a methodfor using a surface layer provided with open hollow chambers, whereinstructuring in the nanometer range is enabled in a simple andcost-effective manner.

One aspect of the present invention is to use a porous oxide layer, andespecially a surface layer, formed via anodic oxidation and providedwith open hollow chambers, as stamping surface of a stamping tool. Thisleads to several advantages.

First, an oxide layer, especially the preferably provided aluminumoxide, is relatively hard. With respect to the often very high stampingforces, this is an advantage for being able to stamp work pieces ofvarious materials and for achieving a long tool life of the stampingtool.

Second, model-free oxidation is very easy and cost-effective to carryout. In particular, producing hollow chambers is (quasi) independent ofthe form and configuration of the cathodes employed, so a model ornegative form is not required, as in electrolytic machining.

Third, the provided model-free forming of open hollow chambers viaanodic oxidation enables structures to be manufactured in the nanometerrange very easily and cost-effectively. In particular, structural widthsof 500 nm and less, even 100 nm and less are possible.

Fourth, depending on choice of procedural conditions theconfiguration—regular or irregular—and the surface density of the hollowchambers can be varied as required.

Fifth, likewise, by simply varying the procedural conditions—especiallyby variation of the voltage during anodizing—the form of the hollowchambers, and thus, the structure of the stamping surface, can beadjusted and varied.

Sixth, the anodally oxidized surface layer can be used directly, thuswithout further molding, as the stamping surface of a stamping tool.

A further aspect of the present invention is to use a porous oxidelayer, and especially a surface layer with open hollow chambers, formedby anodic oxidation directly or model-free, thus independent of acathode form, as molding face or inner face of a casting mold. This hasa number of advantages.

First, an oxide layer, especially the preferably provided aluminumoxide, is relatively hard. With respect to the often very high forcesutilized in casting or molding, this is an advantage for being able toproduce work pieces of various materials and for achieving a long shelflife of the casting mold.

Second, the model-free oxidation is very easy and cost-effective tocarry out. Producing hollow chambers is (quasi) independent on the formand configuration of the cathodes used, and a model or negative form istherefore not required.

Third, the model-free forming of open hollow chambers as provided viaanodic oxidation enables structures to be manufactured in the nanometerrange very easily and cost-effectively. In particular, structural widthsof 500 nm and less, even 100 nm and less are possible.

Fourth, depending on choice of procedural conditions theconfiguration—regular or irregular—and the surface density of the hollowchambers can be varied as required.

Fifth, likewise, by simply varying the procedural conditions—especiallyby variation of the voltage during anodizing—the form of the hollowchambers, and thus, the structure of the surface can be adjusted andvaried.

Sixth, the anodally oxidized surface layer can be used directly, thuswithout further molding, as the surface of a casting mold.

Further advantages, properties, features and goals of the presentinvention will emerge from the following description of preferredembodiments with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a very schematic sectional elevation of a stamping tool and awork piece structured therewith according to a first embodiment; and

FIG. 2 is a very schematic sectional elevation of a proposed castingmold and a work piece structured therewith according to an secondembodiment.

DETAILED DESCRIPTION OF THE INVENTION

In a highly simplified sectional elevation, FIG. 1 shows a proposedstamping tool 1 with a structured, i.e., profiled or relief-like,stamping surface 2. The stamping surface 2 is formed by a side of asurface layer 3 which is provided with open hollow chambers 4 producedby anodic oxidation or an originally flat surface.

In the illustrative example, the surface layer is applied to a support 5of the stamping tool 1. For example, the surface layer 3 is applied tothe support 5 by plasma coating. However, the surface layer 3 can alsobe formed directly by the support 5, and thus can be a surface area ofthe support 5.

It is understood that the surface layer 3 can also be deposited on thesupport 5 using other methods.

In the illustrative example, the surface layer 3 preferably is made ofaluminum which is applied to the support 5, especially via plasmacoating, and adheres well to the support 5, which is preferably made ofmetal, especially iron or steel.

The surface layer 3 is at least partially anodally oxidized in theillustrative example, to the depth of a covering layer 6, whereby thehollow chambers 4 are formed in the surface layer 3. The hollow chambers4 are formed immediately and/or without any model or pattern, i.e., thearrangement, distribution, form and the like of the hollow chambers 4—asopposed to electrolytic machining—is, thus, at least essentiallyindependent of the surface shape and the proximity of the cathode (notshown) used in oxidation. Moreover, according to the invention, the“valve effect,” namely the occurring, independent formation of hollowchambers 4 during oxidation or anodization of the surface layer 3—atleast in particular in the so-called valve metals—is used. Thisimmediate or undefined formation of the hollow chambers 4 does notpreclude an additional (before or after) formation or structuring of thestamping surface 2 or the hollow chambers 4 by means of a negative form.

Depending on how completely or how deeply the surface layer 3 isoxidized, or whether the surface layer 3 is formed directly by thesupport 5, the surface layer 3 can correspond to the oxidized coveringlayer 6. In this case, for example, the intermediate layer 7, which iscomprised of aluminum in the illustrative example, and which promotesvery good adhesion between the covering layer 6 and the support 5, canbe omitted.

For example, according to an alternative embodiment, the uncoatedsupport 5 can be oxidized anodally on its surface forming the stampingsurface 2 by formation of a porous oxide layer or hollow chambers 4.This is possible, for example, for a support 5 made of iron or steel,especially stainless steel. In this case, the surface layer 3 thencorresponds to the covering layer 6, i.e., the oxidized layer.

Aluminum and iron or steel, especially stainless steel, have alreadybeen named as particularly preferred materials, used at leastsubstantially for forming the anodally oxidized surface layer 3 or thecovering layer 6. However, silicon and titanium as well as other valvemetals, for example, can also be used.

In the illustrative example, the proportions in size are not presentedtrue to scale. The stamping tool 1 or its stamping surface 2 preferablyhas a structural width S in the nanometer range, especially from 30 to600 nm and preferably from 50 to 200 nm.

The hollow chambers 4 or their openings have an average diameter D ofessentially 10 to 500 nm, preferably 15 to 200 nm and especially 20 to100 nm.

In the illustrative example, the hollow chambers 4 are designedessentially lengthwise, wherein their depth T is preferably at leastapproximately 0.5 times the above-mentioned, average diameter D andespecially approximately 1.0 to 10 times the diameter D.

Here, the hollow chambers 4 are designed at least substantiallysimilarly in shape. In particular, the hollow chambers 4 are designedsubstantially cylindrically. However, the hollow chambers 4 can alsopresent a form deviating therefrom, for example, they can be designedsubstantially conically.

In general, the hollow chambers 4 can also have a cross-section varyingin its depth T, form and/or diameter. In addition to this, the hollowchambers 4 can be designed substantially conically as a rough structure,for example, and can be provided along their walls with many finedepressions (small hollow chambers) to fonts a fine structure in eachcase.

The hollow chambers 4 are preferably distributed at least substantiallyuniformly over the surface of the surface layer 3 or over the stampingsurface 2. However, uneven distribution is also feasible.

The hollow chambers or their openings are preferably distributed overthe stamping surface 2 with a surface density of 10⁹ to 10¹¹/cm². In theillustrative example, the surface density is substantially constant overthe stamping surface 2. However, the surface density can also varypartially on the stamping surface 2 as required.

The area of the openings of the hollow chambers 4 is, at the most,preferably 50% of the extension area of the stamping surface 2. Asufficiently high stability or carrying capacity of the stamping surface2 or the surface layer 3/covering layer 6 is hereby achieved withrespect to the high stresses arising during the stamping.

In general, the form, configuration, surface density and the like of thehollow chambers 4 can be controlled by corresponding choice of theprocedural conditions during anodic oxidation. For example, withoxidation of aluminium under potentiostatic conditions—with at leastsubstantially constant voltage—an at least substantially evencross-section of the hollow chambers 4 is achieved over their depth T,i.e., an at least substantially cylindrical form. Accordingly, the formof the hollow chambers 4 can be influenced by varying the voltage. Forexample, galvanostatic oxidation—i.e., at an at least substantiallyconstant current—leads to a somewhat conical or hill-like form of thehollow chambers 4, so that a type of “moth eye structure” or the likecan be formed in this way. The surface density of the hollow chambers 4,i.e., the number of hollow chambers 4 per surface unit of the stampingsurface 2, depends inter alia on the voltage and the current duringanodizing.

As required, the hollow chambers 4 can vary in their form, depth and/orsurface density over the stamping surface 2, especially partially,and/or be designed only partly on the stamping surface 2.

If required, the stamping surface 2 can also be modified before and/orafter oxidation—creation of the hollow chambers 4—for example, via alithographic process, etching and/or other, preferablymaterial-stripping methods, for example, to create a rough structure inthe form of paths, ridges, areas with or without hollow chambers 4,large-surface bumps or depressions and the like on the stamping surface2.

Chemical sizing, especially by partial etching of oxide material, canalso be carried out to modify the stamping surface 2 or the hollowchambers 4. In this way, the surface ratio of the opening surfaces ofthe hollow chambers 4 to the extension area of the stamping surface 2can be varied or increased. It is understood that other modifications ofthe stamping surface 2 or of the hollow chambers 4 can also be made,depending on reaction time and intensity.

A particular advantage of the proposed solution is that the stampingsurface 2 can also be designed in a curved manner, for example,cylindrically, bulged, lenticular, or hemispherical. In particular, thestamping surface 2 can have practically any shape at all. Compared tothe prior art, it is thus not necessary that the stamping surface 2 orthe surface of the surface layer 3/covering layer 6 is at leastsubstantially even.

The figure also shows a work piece 8, likewise in a highly simplified,not true-to-scale, sectional diagram, in the already stamped state,i.e., with a surface 9 already structured by the stamping tool 1.Stamping takes places especially by the stamping tool 1 being pressedwith a corresponding stamping force onto the surface 9 of the work piece8 to be structured, so that the material of the work piece 8 flows atleast partially into the hollow chambers 4. Here, it is not necessarythat the work piece 8, as illustrated diagrammatically in the figure, isdesigned in a monobloc manner. Instead, the work piece 8 can alsopresent another type of surface layer or surface coating or the like,not illustrated here, which forms the surface 9 and is structured ordesigned in a relief-like manner by means of the stamping tool 1.

Instead of the stamp-like embossing, the stamping tool 1 can be unrolledwith corresponding shaping/form of the to stamping surface 2 and/or thesurface 9 to be structured. By way of example, the stamping surface 2and/or the surface 9 to be structured can be designed in a curvedmanner—for example, cylindrically—or in a bulged manner, to enablereciprocal unrolling for structuring the surface 9.

Both a die stamping process and also a rolling stamp process can berealized with the proposed solution.

Furthermore, the proposed solution can be used for embossing as well asclosed-die coining or coining. A corresponding abutment for the workpiece 8 or a corresponding countertool is not illustrated forclarification purposes.

The proposed stamping tool 1 allows very fine structuring of the workpiece 8 or its surface 9. If needed, the work piece 8 or the surface 9can also be profiled or structured repeatedly, first with a roughstructured stamping tool—optionally manufactured also in customaryfashion—and then with the finer structured stamping tool 1 proposedhere. A lower stamping force is employed, especially during the secondstamping procedure using the finer stamping tool 1 and/or, in anintermediate step, the surface 9 is hardened in order not to fullyneutralize the rough structure produced at first stamping, but toachieve superposition from the rough structure and the fine structure ofboth stamping tools. Thus, it is possible, for example, to create on thesurface 9 relatively large bumps of the order of 0.1 to 50 μm, each withseveral, relatively small protrusions, for example, of the order of 10to 400 nm, on the surface 9 of the work piece 8.

The proposed solution very easily and cost-effectively enables very finestructuring of the surface 9. Accordingly, there is a very broad area ofapplication. For example, such especially very fine structuring can beutilized in anti-reflex layers, for altering radiation emission ofstructured surfaces, in sensory analysis, in catalysis, in self-cleaningsurfaces, in improving surface wettability and the like. In particular,the proposed solution also extends to the use of work pieces 8 withstructured surfaces 9 that have been structured by use of the proposedstamping tool 1 for the purposes mentioned hereinabove.

In particular, the proposed solution is suited for stamping syntheticmaterials—for example, PMMA (polymethyl methacrylates), Teflon or thelike, metals—for example, gold, silver, platinum, lead, indium, cadmium,zinc or the like, polymer coatings—for example, paints, dyes or thelike, and inorganic coating systems etc.

Expressed in general terms, an essential aspect of the present inventionaccording to the first embodiment is using a surface layer with hollowchambers formed by anodic oxidation as a bottom die or upper die, toenable surface structuring in the nanometer range.

Now, the second embodiment of the present invention is discussed withreference to FIG. 2.

In a highly simplified partial sectional elevation, FIG. 2 shows aproposed casting mold 11 with an at least partially structured, thusprofiled or relief-like inner face or molding face 12. The face 12 isformed by a top or flat side of a surface layer 13 that is provided withopen hollow chambers 14 produced by anodic oxidation.

In the illustrative example, the surface layer 13 is applied to asupport 15 of the casting mold 11. For example, the surface layer 13 isapplied to the support 15 by plasma coating. However, the surface layer13 can also be formed directly by the support 15, and thus can be asurface area of the support 15.

It is understood that the surface layer 13 can also be deposited on thesupport 15 using other methods.

In the illustrative example, the surface layer 13 preferably comprisesaluminum, which is applied to the support 15 especially via plasmacoating, and adheres well to the support 15 that is preferably made ofmetal, especially iron or steel.

The surface layer 13 is at least partially anodally oxidized, in theillustrative example, to the depth of a covering layer 16, by means ofwhich the hollow chambers 14 are formed in the surface layer 13 orcovering layer 16. The hollow chambers 14 are formed directly ormodel-free, that is, the configuration, distribution, form and the likeof the hollow chambers 14 is, compared to electrolytic machining,therefore at least substantially dependent on the surface shape andproximity of the cathodes (not illustrated here) used during oxidation.Rather, the ‘valve effect’ is made use of here, as per the invention,namely the automatic development of the hollow chambers 14 occurringduring oxidation or anodizing of the surface layer 13, at leastespecially with so-called valve metals. Such direct and model-freeproduction of the hollow chambers 14 does not exclude additional (prioror subsequent) forming or structuring of the face 12 or of the hollowchambers 14 by a negative form.

Depending on how completely or how deeply the surface layer 13 isoxidized, or whether the surface layer 13 is formed directly by thesupport 15, the surface layer 13 can correspond to the oxidized coveringlayer 16. In the illustrative example, in this case, for example, theintermediate layer 17, which is comprised of aluminum and which promotesvery good adhesion between the covering layer 16 and the support 15, canbe omitted.

For example, according to a design alternative the uncoated support 15can be oxidized anodally on its surface forming the face 12 by formationof a porous oxide layer or hollow chambers 14. This is possible forexample, for a support 15 made of iron or steel, especially stainlesssteel. In this case the surface layer 13 then corresponds to thecovering layer 16, i.e., the oxidized layer.

Aluminum and iron or steel, especially stainless steel, have alreadybeen named as particularly preferred materials, used at leastsubstantially for forming the anodally oxidized surface layer 13 or thecovering layer 16. However, silicon and titanium as well as other valvemetals for example, can also be used.

In the illustrative example, the proportions in size are not presentedtrue to scale. The face 12 preferably has a structural width S in thenanometer range, especially of 130 to 600 nm and preferably of 50 to 200nm. The hollow chambers 14 or their openings have an average diameter Dof essentially 10 to 500 nm, preferably 15 to 200 nm and especially 20to 100 nm.

In the illustrative example, the hollow chambers 14 are designedessentially lengthwise, wherein their depth T is preferably at leastapproximately 0.5 times the above-mentioned, average diameter D andespecially approximately 1.0 to 10 times the diameter D.

The hollow chambers 14 are designed, here, at least substantiallyidentically. In particular, the hollow chambers 14 are designedsubstantially cylindrically. However, the hollow chambers 14 can alsopresent a form deviating therefrom, for example, they can be designedsubstantially conically.

In general the hollow chambers 14 can also have a cross-section varyingin its depth T in form and/or diameter. In addition to this, the hollowchambers 14 can be designed substantially conically as a roughstructure, for example, and can be provided with many fine depressions(small hollow chambers) along their walls to form a fine structure ineach case.

The hollow chambers 14 are preferably distributed at least substantiallyuniformly over the surface of the surface layer 13 or over the face 12.However, uneven distribution is also feasible.

The hollow chambers or their openings are preferably distributed with asurface density of 10⁹ to 10¹¹/cm. In the illustrative example, thesurface density is substantially constant over the face 12. However, thesurface density can also vary selectively on the surface 12 as required.

The area of the openings of the hollow chambers 14 is at the mostpreferably 50% of the extension area of the face 12. A sufficiently highstability or carrying capacity of the face 12 or the surface layer13/covering layer 16 is thereby achieved with respect to the highstresses arising partially from molding or casting.

In general, the form, configuration, surface density and the like of thehollow chambers 14 can be controlled by corresponding choice of theprocedural conditions during anodic oxidation. For example, withoxidation of aluminium under potentiostatic conditions—i.e., at least atsubstantially constant voltage—an at least substantially uniformcross-section of the hollow chambers 14 is achieved over their depth T,i.e., an at least substantially cylindrical form. Accordingly, the formof the hollow chambers 14 can be influenced by varying the voltage. Forexample, galvanostatic oxidation, i.e., at an at least substantiallyconstant current, leads to a somewhat conical or hill-like form of thehollow chambers 14, so that a type of “moth eye structure” or the likecan be formed in this way. The area density of the hollow chambers 14,i.e., the number of hollow chambers 14 per area unit on the face 2,depends inter alia on the voltage and the current during anodizing.

As required, the hollow chambers 14 can vary in their form, depth and/orsurface density over the face 2, especially partially, and/or bedesigned only partially on the face 12.

And, if required, the face 12 can also be modified before and/or afteroxidation—thus, creation of the hollow chambers 14—for example, via alithographic process, etching and/or other, preferablymaterial-stripping methods, for example, to create a rough structure inthe form of paths, ridges, areas with or without hollow chambers 14,large-surface bumps or depressions and the like on the face 12.

Mechanical processing and/or chemical sizing, especially by partialetching of oxide material, can also be carried out to modify the face 12or the hollow chambers 14. In this way, the area ratio of the openingareas of the hollow chambers 14 to the extension area of the face 12 canbe varied or increased. It is understood that other modifications of theface 12 or of the hollow chambers 14 can also be made, depending onreaction time and intensity.

A particular advantage of the proposed solution is that the face 12 canalso be designed in practically any shape at all.

The figure also shows a molded article or work piece 18, likewise in ahighly simplified, not true-to-scale, sectional diagram, in the alreadyfinished state, i.e., with a surface 19 already structured by thecasting mold 11 after casting.

The proposed casting mold 11 allows very fine structuring of the workpiece 18 or its surface 19. It is possible, for example, to createrelatively large bumps of the order of 0.1 to 50 μm each with several,relatively small projections on the surface 19, for example, of theorder of 10 to 400 nm, on the surface 19 of the work piece 18.

The proposed solution very easily and cost-effectively enables very finestructuring of the surface 19. Accordingly, there is a very broad areaof application. For example, such especially very fine structuring canbe utilized in anti-reflex layers, for altering radiation emission ofstructured surfaces, in sensory analysis, in catalysis, in self-cleaningsurfaces, in improving surface wettability and the like.

Expressed in general terms, an essential aspect of the present inventionis casting or molding a surface layer with hollow chambers formeddirectly or model-free by anodic oxidation, to enable surfacestructuring in the nanometer range.

The present invention is especially not limited to a casting mold 11 inthe narrower sense. Rather, the surface layer 13 or covering layer 16 isto be understood as model for a general structuring of a surface, atool, a work piece or the like in the nanometer range. In particular,the model may be molded in any way at all. In particular, no reshapingis required when molding. For example, with the work piece 18 to bemanufactured having a structured surface 19, this can be a cast article,wherein the surface 19 is structured by casting or decanting or anymolding of the mold 11.

In general, the present invention enables a simple, cost-effectivestamping or molding in the nanometer range by a surface layer withhollow chambers formed by anodic oxidation being used as matrix or ascasting mold.

TECHNICAL APPLICABILITY

The proposed solution very easily and cost-effectively enables very finestructuring of the surface. Accordingly, there is a very broad area ofapplication. For example, such especially very fine structuring can beutilized in anti-reflex layers, for altering radiation emission ofstructured surfaces, in sensory analysis, in catalysis, in self-cleaningsurfaces, in improving surface wettability and the like. In particular,the proposed solution also extends to the use of work pieces withstructured surfaces that have been structured by use of the proposedstamping tool for the purposes mentioned hereinabove. Further, theproposed solution can be used for casting with practically any material,since aluminum oxide especially is highly resistant mechanically,thermally and/or chemically.

What is claimed is:
 1. Method for producing a stamping tool with astructured stamping surface, comprising the steps of: oxidizing asurface or covering layer of the stamping tool for forming the stampingsurface at least partially anodally and forming open hollow chambersthat are at least essentially uniformly shaped and at least essentiallyevenly distributed over the surface or surface area of the stampingsurface without the use of a model.
 2. Method according to claim 1,wherein the surface or covering layer is oxidized potentiostatically. 3.Method according to claim 1, wherein the surface layer or covering layeris oxidized with varying voltage.
 4. Method according to claim 3,wherein the surface or covering layer is oxidized galvanostatically. 5.Method according to claim 1, wherein the surface or covering layer thatis oxidized is formed of a material selected from the group consistingof aluminum, silicon, iron, steel and titanium.
 6. Method according toclaim 1, comprising the additional step of modifying the stampingsurface at least one of before and after said oxidizing step forproducing a rough structure.
 7. Method for structuring a surface of awork piece in a nanometer range by means of a stamping tool with astructured stamping surface, comprising at least one of pressing androlling a stamping surface, formed of an anodally oxidized surface orcovering layer with open hollow chambers which have diameters in ananometer range that have been created model-free by anodic oxidation,onto the surface to be structured.
 8. Method according to claim 7,wherein the surface is first roughly structured in a first step by meansof a first stamping tool and then is finely structured by means of asecond stamping tool in a second step.
 9. Method according to claim 8,wherein the surface is finely structured by means of said secondstamping tool in said second step with a stamping force that is reducedrelative to that applied with said first stamping tool.
 10. Methodaccording to claim 8, wherein the surface is finely structured by meansof said second stamping tool in said second step after hardening of thesurface structured by said first step.
 11. Method for at least partiallystructuring a surface of a cast work piece, comprising the steps of:casting the work piece using a casting mold with a structured moldingface having an anodally oxidized surface or covering layer with openhollow chambers created model-free by anodic oxidation.
 12. Methodaccording to claim 11, wherein the surface or covering layer is formedat least substantially of a material selected from the group consistingof aluminum oxide, silicon oxide, iron oxide, oxidized steel, andtitanium oxide.
 13. An anti-reflection surface, comprising: a surfaceincluding at least one of projections of diameters in a nanometer range,and hollow chambers including diameters in a nanometer range, whereinthe at least one of projections and hollow chambers on theanti-reflection surface are irregularly distributed, and wherein groupsof the projections form larger projections of an order ranging from0.1-50 micrometers, the larger projections including a surface havingadditional projections of 10-400 nm.
 14. The anti-reflection surfaceaccording to claim 13, wherein the surface comprises an anodicallyoxidized material selected from the group consisting of aluminum,silicon, iron, steel and titanium.
 15. The anti-reflection surface ofclaim 13, wherein the hollow chambers include diameters ranging from10-500 nanometers.
 16. The anti-reflection surface of claim 15, whereinthe hollow chambers include diameters ranging from 15-200 nanometers.17. The anti-reflection surface of claim 16, wherein the hollow chambersinclude diameters ranging from 20-100 nanometers.
 18. Theanti-reflection surface of claim 13, wherein the projections includediameters ranging from 10-400 nanometers.
 19. A device, comprising theanti-reflection surface of claim
 13. 20. A workpiece, comprising theanti-reflection surface of claim
 13. 21. A device, comprising aworkpiece, wherein the anti-reflection surface of claim 13 is a surfaceof the workpiece.
 22. The anti-reflection surface of claim 13, whereinthe projections include irregularly shaped projections.
 23. Theanti-reflection surface of claim 13, wherein the projections are of asomewhat conical shape.
 24. The anti-reflection surface of claim 13,wherein the hollow chambers are irregularly shaped hollow chambers. 25.The anti-reflection surface of claim 13, wherein the hollow chambers areof a somewhat conical shape.
 26. The anti-reflection surface of claim13, wherein the anti-reflection surface is formed from an acrylic resin.27. The anti-reflection surface of claim 26, wherein the acrylic resinis PMMA.
 28. The anti-reflection surface of claim 13, wherein the hollowchambers include structural widths ranging from 30-600 nanometers. 29.An anti-reflection surface, comprising: a surface including at least oneof projections and hollow chambers distributed over the surface at adensity of 10⁹ to 10¹¹/cm², wherein the at least one of projections andhollow chambers have a substantially conical shape.
 30. Theanti-reflection surface according to claim 29, wherein theanti-reflection surface is formed of an anodically oxidized materialselected from the group consisting of aluminum, silicon, iron, steel andtitanium.
 31. The anti-reflection surface of claim 29, wherein thehollow chambers of the anti-reflection surface includes diametersranging from 10-500 nanometers.
 32. The anti-reflection surface of claim31, wherein the hollow chambers include diameters ranging from 15-200nanometers.
 33. The anti-reflection surface of claim 32, wherein thehollow chambers include diameters ranging from 20-100 nanometers. 34.The anti-reflection surface of claim 29, wherein the projections includediameters ranging from 10-400 nanometers.
 35. The anti-reflectionsurface of claim 34, wherein groups of the projections form largerprojections of an order ranging from 0.1-50 micrometers.
 36. A device,comprising the anti-reflection surface of claim
 29. 37. A workpiece,comprising the anti-reflection surface of claim
 29. 38. A device,comprising a workpiece, wherein the anti-reflection surface of claim 29is a surface of the workpiece.
 39. The anti-reflection surface of claim29, wherein the hollow chambers of the anti-reflection surface includesirregularly distributed hollow chambers.
 40. The anti-reflection surfaceof claim 29, wherein the anti-reflection surface includes irregularlyshaped hollow chambers.
 41. The anti-reflection surface of claim 29,wherein the anti-reflection surface includes irregularly distributedprojections.
 42. The anti-reflection surface of claim 29, wherein theanti-reflection surface includes irregularly shaped projections.
 43. Theanti-reflection surface of claim 29, wherein the anti-reflection surfaceis formed from an acrylic resin.
 44. The anti-reflection surface ofclaim 43, wherein the acrylic resin is PMMA.
 45. The anti-reflectionsurface of claim 29, wherein the anti-reflection surface includes hollowchambers with structural widths ranging from 30-600 nanometers.